French patent application No. 90 08479 filed Jul. 4, 1990 in the name of the present Applicant describes a system for integrated pitch and thrust control of an aircraft comprising:
first airfoils for pitch control actuated from a first actuator member associated with a first transducer delivering a first electrical signal representative of the trim setting;
at least one engine controlled from a second actuator member associated with a second transducer delivering a second electrical signal representative of a speed setting for said aircraft;
a plurality of second airfoils, at least some of which are capable of taking up different determined positions as a function of each stage of flight of the aircraft, defining particular aerodynamic configurations, with the choice of one or other of said aerodynamic configurations being obtained by actuating a third actuator member associated with a third transducer delivering a third electrical signal representative of the selected configuration;
means suitable for delivering a fourth electrical signal representative of the mass of said aircraft;
means suitable for delivering a fifth electrical signal representative of the distance along the longitudinal axis of said aircraft between the center of gravity of said aircraft and an origin; and
means suitable for delivering sixth, seventh, eighth, ninth, and tenth electrical signals respectively representative of the instantaneous flight altitude, aerodynamic angle of incidence, pitch rate, longitudinal trim, and speed of said aircraft;
said control system being remarkable in that it includes:
a first calculation device receiving said first to sixth electrical signals together with said tenth electrical signal and delivering first and second linear combinations of said first and second electrical signals, with the coefficients given to said first and second electrical signals respectively in said first and second linear combinations depending on said third to sixth and tenth electrical signals;
a second calculation device receiving said third to tenth electrical signals and generating third and fourth linear combinations of said seventh to tenth electrical signals, the coefficients given to said seventh to tenth electrical signals respectively in said third and fourth linear combinations depending on said third to sixth and tenth electrical signals;
first adder means receiving said first and third linear combinations and adding them to form a pitch first electrical command applied to said first airfoils; and
second adder means receiving said second and fourth linear combinations and adding them to form a thrust second electrical command applied to said engine.
A system for integrated pitch and thrust control is thus obtained in which each of the pitch and thrust commands is a linear combination including static parameters (trim setting and speed setting) and dynamic parameters (instantaneous speed, longitudinal trim, pitch rate, and angle of incidence). Such a system can thus reduce the workload on the pilot while simultaneously providing greater safety and improving the comfort of passengers in the aircraft.
An object of the present invention is to improve the above-outlined integrated control system, in particular to enable the trim of the aircraft to be locked in turbulence so long as said first actuator member is in a neutral position.